The book, "The Pedophile's Guide to Love and Pleasure: a Child-lover's Code of Conduct," offers advice to pedophiles on how to make a sexual encounter with a child as safe as possible. It includes first-person descriptions of such encounters, purportedly written from a child's point of view.

The availability of the book calls into question whether Amazon has any procedures — or even an obligation — to vet books before they are sold in its online stores. The title is an electronic book available for Amazon's Kindle e-reader and the company's software for reading Kindle books on mobile phones and computers. Amazon allows authors to submit their own works and shares revenue with them.

Amazon issues guidelines banning certain materials, including those deemed offensive. However, the company doesn't elaborate on what constitutes offensive content, saying simply that it is "probably what you would expect." Amazon also doesn't promise to remove or protect any one category of books.

Once discovered Wednesday, the book triggered outrage from commenters on sites such as Twitter. Some people threatened to boycott the online store until Amazon removed the book. Two petitions on Facebook alone won more than 13,500 supporters.

On Wednesday, child online safety advocacy group Enough is Enough says it isn't surprised that someone would publish such a book, but believes that Amazon should remove it. It says selling the book lends the impression that child abuse is normal.

But Christopher Finan, president of the American Booksellers Foundation for Free Expression, said Amazon has the right under the First Amendment to sell any book that is not child pornography or legally obscene. Finan said Greaves' book doesn't amount to either because it does not include illustrations.

This isn't the first time Amazon has sold material that promotes illegal activity. It is currently accepting pre-orders for the hardcover version of "I Am the Market: How to Smuggle Cocaine by the Ton, in Five Easy Lessons" by Luca Rastello.

Nor is it the first time Amazon has come under attack for selling objectionable content in its store. In 2002, the United States Justice Foundation, a conservative group, threatened to sue Amazon for selling "Understanding Loved Boys and Boylovers." That title is still available through Amazon.

In 2009, Amazon stopped selling "RapeLay," a first-person video game in which the protagonist stalks and then rapes a mother and her daughters, after it was widely condemned in the media and by various interest groups.

The author of "The Pedophile's Guide," listed as Philip R. Greaves II, still has other titles sold through Amazon.